Merge tag 'rust-7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/ojeda/linux

Pull Rust updates from Miguel Ojeda:
 "Toolchain and infrastructure:

   - Bump the minimum Rust version to 1.85.0 (and 'bindgen' to 0.71.1).

     As proposed in LPC 2025 and the Maintainers Summit [1], we are
     going to follow Debian Stable's Rust versions as our minimum
     versions.

     Debian Trixie was released on 2025-08-09 with a Rust 1.85.0 and
     'bindgen' 0.71.1 toolchain, which is a fair amount of time for e.g.
     kernel developers to upgrade.

     Other major distributions support a Rust version that is high
     enough as well, including:

       + Arch Linux.
       + Fedora Linux.
       + Gentoo Linux.
       + Nix.
       + openSUSE Slowroll and openSUSE Tumbleweed.
       + Ubuntu 25.10 and 26.04 LTS. In addition, 24.04 LTS using
         their versioned packages.

     The merged patch series comes with the associated cleanups and
     simplifications treewide that can be performed thanks to both
     bumps, as well as documentation updates.

     In addition, start using 'bindgen''s '--with-attribute-custom-enum'
     feature to set the 'cfi_encoding' attribute for the 'lru_status'
     enum used in Binder.

     Link: https://lwn.net/Articles/1050174/ [1]

   - Add experimental Kconfig option ('CONFIG_RUST_INLINE_HELPERS') that
     inlines C helpers into Rust.

     Essentially, it performs a step similar to LTO, but just for the
     helpers, i.e. very local and fast.

     It relies on 'llvm-link' and its '--internalize' flag, and requires
     a compatible LLVM between Clang and 'rustc' (i.e. same major
     version, 'CONFIG_RUSTC_CLANG_LLVM_COMPATIBLE'). It is only enabled
     for two architectures for now.

     The result is a measurable speedup in different workloads that
     different users have tested. For instance, for the null block
     driver, it amounts to a 2%.

   - Support global per-version flags.

     While we already have per-version flags in many places, we didn't
     have a place to set global ones that depend on the compiler
     version, i.e. in 'rust_common_flags', which sometimes is needed to
     e.g. tweak the lints set per version.

     Use that to allow the 'clippy::precedence' lint for Rust < 1.86.0,
     since it had a change in behavior.

   - Support overriding the crate name and apply it to Rust Binder,
     which wanted the module to be called 'rust_binder'.

   - Add the remaining '__rust_helper' annotations (started in the
     previous cycle).

  'kernel' crate:

   - Introduce the 'const_assert!' macro: a more powerful version of
     'static_assert!' that can refer to generics inside functions or
     implementation bodies, e.g.:

         fn f<const N: usize>() {
             const_assert!(N > 1);
         }

         fn g<T>() {
             const_assert!(size_of::<T>() > 0, "T cannot be ZST");
         }

     In addition, reorganize our set of build-time assertion macros
     ('{build,const,static_assert}!') to live in the 'build_assert'
     module.

     Finally, improve the docs as well to clarify how these are
     different from one another and how to pick the right one to use,
     and their equivalence (if any) to the existing C ones for extra
     clarity.

   - 'sizes' module: add 'SizeConstants' trait.

     This gives us typed 'SZ_*' constants (avoiding casts) for use in
     device address spaces where the address width depends on the
     hardware (e.g. 32-bit MMIO windows, 64-bit GPU framebuffers, etc.),
     e.g.:

         let gpu_heap = 14 * u64::SZ_1M;
         let mmio_window = u32::SZ_16M;

   - 'clk' module: implement 'Send' and 'Sync' for 'Clk' and thus
     simplify the users in Tyr and PWM.

   - 'ptr' module: add 'const_align_up'.

   - 'str' module: improve the documentation of the 'c_str!' macro to
     explain that one should only use it for non-literal cases (for the
     other case we instead use C string literals, e.g. 'c"abc"').

   - Disallow the use of 'CStr::{as_ptr,from_ptr}' and clean one such
     use in the 'task' module.

   - 'sync' module: finish the move of 'ARef' and 'AlwaysRefCounted'
     outside of the 'types' module, i.e. update the last remaining
     instances and finally remove the re-exports.

   - 'error' module: clarify that 'from_err_ptr' can return 'Ok(NULL)',
     including runtime-tested examples.

     The intention is to hopefully prevent UB that assumes the result of
     the function is not 'NULL' if successful. This originated from a
     case of UB I noticed in 'regulator' that created a 'NonNull' on it.

  Timekeeping:

   - Expand the example section in the 'HrTimer' documentation.

   - Mark the 'ClockSource' trait as unsafe to ensure valid values for
     'ktime_get()'.

   - Add 'Delta::from_nanos()'.

  'pin-init' crate:

   - Replace the 'Zeroable' impls for 'Option<NonZero*>' with impls of
     'ZeroableOption' for 'NonZero*'.

   - Improve feature gate handling for unstable features.

   - Declutter the documentation of implementations of 'Zeroable' for
     tuples.

   - Replace uses of 'addr_of[_mut]!' with '&raw [mut]'.

  rust-analyzer:

   - Add type annotations to 'generate_rust_analyzer.py'.

   - Add support for scripts written in Rust ('generate_rust_target.rs',
     'rustdoc_test_builder.rs', 'rustdoc_test_gen.rs').

   - Refactor 'generate_rust_analyzer.py' to explicitly identify host
     and target crates, improve readability, and reduce duplication.

  And some other fixes, cleanups and improvements"

* tag 'rust-7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/ojeda/linux: (79 commits)
  rust: sizes: add SizeConstants trait for device address space constants
  rust: kernel: update `file_with_nul` comment
  rust: kbuild: allow `clippy::precedence` for Rust < 1.86.0
  rust: kbuild: support global per-version flags
  rust: declare cfi_encoding for lru_status
  docs: rust: general-information: use real example
  docs: rust: general-information: simplify Kconfig example
  docs: rust: quick-start: remove GDB/Binutils mention
  docs: rust: quick-start: remove Nix "unstable channel" note
  docs: rust: quick-start: remove Gentoo "testing" note
  docs: rust: quick-start: add Ubuntu 26.04 LTS and remove subsection title
  docs: rust: quick-start: update minimum Ubuntu version
  docs: rust: quick-start: update Ubuntu versioned packages
  docs: rust: quick-start: openSUSE provides `rust-src` package nowadays
  rust: kbuild: remove "dummy parameter" workaround for `bindgen` < 0.71.1
  rust: kbuild: update `bindgen --rust-target` version and replace comment
  rust: rust_is_available: remove warning for `bindgen` < 0.69.5 && libclang >= 19.1
  rust: rust_is_available: remove warning for `bindgen` 0.66.[01]
  rust: bump `bindgen` minimum supported version to 0.71.1 (Debian Trixie)
  rust: block: update `const_refs_to_static` MSRV TODO comment
  ...

3 files changed, 24 insertions, 36 deletions

diff --git a/Documentation/process/changes.rst b/Documentation/process/changes.rst
index 6b373e193548..84156d031365 100644
--- a/Documentation/process/changes.rst
+++ b/Documentation/process/changes.rst
@@ -31,8 +31,8 @@ you probably needn't concern yourself with pcmciautils.
 ====================== ===============  ========================================
 GNU C                  8.1              gcc --version
 Clang/LLVM (optional)  15.0.0           clang --version
-Rust (optional)        1.78.0           rustc --version
-bindgen (optional)     0.65.1           bindgen --version
+Rust (optional)        1.85.0           rustc --version
+bindgen (optional)     0.71.1           bindgen --version
 GNU make               4.0              make --version
 bash                   4.2              bash --version
 binutils               2.30             ld -v
diff --git a/Documentation/rust/general-information.rst b/Documentation/rust/general-information.rst
index 6146b49b6a98..09234bed272c 100644
--- a/Documentation/rust/general-information.rst
+++ b/Documentation/rust/general-information.rst
@@ -157,5 +157,5 @@ numerical comparisons, one may define a new Kconfig symbol:
 
 .. code-block:: kconfig
 
-	config RUSTC_VERSION_MIN_107900
-		def_bool y if RUSTC_VERSION >= 107900
+	config RUSTC_HAS_SPAN_FILE
+		def_bool RUSTC_VERSION >= 108800
diff --git a/Documentation/rust/quick-start.rst b/Documentation/rust/quick-start.rst
index 152289f0bed2..a6ec3fa94d33 100644
--- a/Documentation/rust/quick-start.rst
+++ b/Documentation/rust/quick-start.rst
@@ -57,8 +57,8 @@ of the box, e.g.::
 Gentoo Linux
 ************
 
-Gentoo Linux (and especially the testing branch) provides recent Rust releases
-and thus it should generally work out of the box, e.g.::
+Gentoo Linux provides recent Rust releases and thus it should generally work out
+of the box, e.g.::
 
 	USE='rust-src rustfmt clippy' emerge dev-lang/rust dev-util/bindgen
 
@@ -68,8 +68,8 @@ and thus it should generally work out of the box, e.g.::
 Nix
 ***
 
-Nix (unstable channel) provides recent Rust releases and thus it should
-generally work out of the box, e.g.::
+Nix provides recent Rust releases and thus it should generally work out of the
+box, e.g.::
 
 	{ pkgs ? import <nixpkgs> {} }:
 	pkgs.mkShell {
@@ -84,16 +84,13 @@ openSUSE
 openSUSE Slowroll and openSUSE Tumbleweed provide recent Rust releases and thus
 they should generally work out of the box, e.g.::
 
-	zypper install rust rust1.79-src rust-bindgen clang
+	zypper install rust rust-src rust-bindgen clang
 
 
 Ubuntu
 ******
 
-25.04
-~~~~~
-
-The latest Ubuntu releases provide recent Rust releases and thus they should
+Ubuntu 25.10 and 26.04 LTS provide recent Rust releases and thus they should
 generally work out of the box, e.g.::
 
 	apt install rustc rust-src bindgen rustfmt rust-clippy
@@ -112,33 +109,33 @@ Though Ubuntu 24.04 LTS and older versions still provide recent Rust
 releases, they require some additional configuration to be set, using
 the versioned packages, e.g.::
 
-	apt install rustc-1.80 rust-1.80-src bindgen-0.65 rustfmt-1.80 \
-		rust-1.80-clippy
-	ln -s /usr/lib/rust-1.80/bin/rustfmt /usr/bin/rustfmt-1.80
-	ln -s /usr/lib/rust-1.80/bin/clippy-driver /usr/bin/clippy-driver-1.80
+	apt install rustc-1.85 rust-1.85-src bindgen-0.71 rustfmt-1.85 \
+		rust-1.85-clippy
+	ln -s /usr/lib/rust-1.85/bin/rustfmt /usr/bin/rustfmt-1.85
+	ln -s /usr/lib/rust-1.85/bin/clippy-driver /usr/bin/clippy-driver-1.85
 
 None of these packages set their tools as defaults; therefore they should be
 specified explicitly, e.g.::
 
-	make LLVM=1 RUSTC=rustc-1.80 RUSTDOC=rustdoc-1.80 RUSTFMT=rustfmt-1.80 \
-		CLIPPY_DRIVER=clippy-driver-1.80 BINDGEN=bindgen-0.65
+	make LLVM=1 RUSTC=rustc-1.85 RUSTDOC=rustdoc-1.85 RUSTFMT=rustfmt-1.85 \
+		CLIPPY_DRIVER=clippy-driver-1.85 BINDGEN=bindgen-0.71
 
-Alternatively, modify the ``PATH`` variable to place the Rust 1.80 binaries
+Alternatively, modify the ``PATH`` variable to place the Rust 1.85 binaries
 first and set ``bindgen`` as the default, e.g.::
 
-	PATH=/usr/lib/rust-1.80/bin:$PATH
+	PATH=/usr/lib/rust-1.85/bin:$PATH
 	update-alternatives --install /usr/bin/bindgen bindgen \
-		/usr/bin/bindgen-0.65 100
-	update-alternatives --set bindgen /usr/bin/bindgen-0.65
+		/usr/bin/bindgen-0.71 100
+	update-alternatives --set bindgen /usr/bin/bindgen-0.71
 
-``RUST_LIB_SRC`` needs to be set when using the versioned packages, e.g.::
+``RUST_LIB_SRC`` may need to be set when using the versioned packages, e.g.::
 
-	RUST_LIB_SRC=/usr/src/rustc-$(rustc-1.80 --version | cut -d' ' -f2)/library
+	RUST_LIB_SRC=/usr/src/rustc-$(rustc-1.85 --version | cut -d' ' -f2)/library
 
 For convenience, ``RUST_LIB_SRC`` can be exported to the global environment.
 
-In addition, ``bindgen-0.65`` is available in newer releases (24.04 LTS and
-24.10), but it may not be available in older ones (20.04 LTS and 22.04 LTS),
+In addition, ``bindgen-0.71`` is available in newer releases (24.04 LTS),
+but it may not be available in older ones (20.04 LTS and 22.04 LTS),
 thus ``bindgen`` may need to be built manually (please see below).
 
 
@@ -355,12 +352,3 @@ Hacking
 To dive deeper, take a look at the source code of the samples
 at ``samples/rust/``, the Rust support code under ``rust/`` and
 the ``Rust hacking`` menu under ``Kernel hacking``.
-
-If GDB/Binutils is used and Rust symbols are not getting demangled, the reason
-is the toolchain does not support Rust's new v0 mangling scheme yet.
-There are a few ways out:
-
-- Install a newer release (GDB >= 10.2, Binutils >= 2.36).
-
-- Some versions of GDB (e.g. vanilla GDB 10.1) are able to use
-  the pre-demangled names embedded in the debug info (``CONFIG_DEBUG_INFO``).